claude-code - 💡(How to fix) Fix [Bug] UserPromptSubmit hook error: Missing required field "hookEventName" in hookSpecificOutput [1 participants]

[{"error":"Error: NON-FATAL: Lock acquisition failed for /home/nix010825/.local/share/claude/versions/2.1.126 (expected in multi-process scenarios)\n at n68 (/$bunfs/root/src/entrypoints/cli.js:2770:2177)\n at sM6 (/$bunfs/root/src/entrypoints/cli.js:2770:1257)\n at processTicksAndRejections (native:7:39)","timestamp":"2026-05-01T02:02:37.358Z"}]

TL;DR

The issue is likely caused by a missing required field "hookEventName" in the hookSpecificOutput, which can be fixed by ensuring the output validation includes this field.

Guidance

• Review the UserPromptSubmit hook configuration to ensure it includes the required "hookEventName" field in its output.
• Verify that the hookSpecificOutput is correctly formatted and includes all necessary fields, including "hookEventName".
• Check the documentation for the UserPromptSubmit hook to confirm the required output fields and their formats.
• Investigate the error message "Lock acquisition failed" to determine if it's related to the main issue or a separate problem.

Example

No code snippet is provided as the issue does not include sufficient code context.

Notes

The "Lock acquisition failed" error may be a separate issue related to multi-process scenarios, and its relation to the main problem is unclear.

Recommendation

Apply workaround: Ensure the "hookEventName" field is included in the hookSpecificOutput to resolve the JSON output validation error, and investigate the "Lock acquisition failed" error separately.